Ruegg et al U.S. Pat. No. 4,129,280 is directed to a clamp with two degrees of freedom. A resilient spring provides braking to minimize positioning problems.
Monticelli et al U.S. Pat. No. 4,299,370 describes a fixture having translation and rotation about an axis which may be handled independently. Two knobs control these characteristics.
Reedy et al U.S. Pat. No. 4,426,055 covers apparatus for aligning optical devices. McDonough U.S. Pat. No. 4,575,033 shows a typical post clamp.